Банан мягче, чем груша, если он полежит на кухне пару дней.

In Russian, the verb быть (to be) is usually not expressed in the present tense.

So:

• Банан мягче, чем груша = A banana is softer than a pear
• literally: Banana softer than pear

This is completely normal. Russian only uses forms of быть in the past, future, or in special styles.

Russian has no articles, so nouns like банан and груша can mean:

• a banana / the banana
• a pear / the pear

The context tells you which is meant. In this sentence, English naturally uses a banana and a pear, but Russian does not mark that difference.

Мягче is the comparative form of мягкий (soft), so it means softer.

Russian often uses a single-word comparative instead of a phrase like more soft:

• мягкий = soft
• мягче = softer

You can sometimes say более мягкий (more soft / softer), but мягче is more natural and common here.

This is one of the common comparative patterns in Russian, where the adjective stem changes a bit.

• мягкий → мягче

The change is not fully predictable from English, so it is best learned as a vocabulary pattern. Many Russian comparatives are like this:

• тихий → тише
• дорогой → дороже
• мягкий → мягче

So for a learner, the main thing is: мягче is simply the standard comparative form of мягкий.

Чем is the normal Russian word for than in comparisons.

Pattern:

• X + comparative + чем + Y

So:

• Банан мягче, чем груша = A banana is softer than a pear

This is the most straightforward and neutral way to make a comparison.

In a basic comparison like this, the noun after чем is commonly left in the nominative form:

• чем груша
• чем брат
• чем машина

So груша stays in its dictionary form.

For a beginner, the safest rule is: after чем in a simple comparison, use the normal noun form unless you know a specific different pattern.

Yes, он refers to банан.

Russian pronouns agree with the grammatical gender of the noun:

• банан is masculine → он
• груша is feminine → она

So even though English would say it, Russian says:

• он for банан
• она for груша

Here, он clearly points back to банан.

Because the sentence is talking about a condition that would happen in the future or under certain circumstances.

• если он лежит = if it is lying / if it is lying now
• если он полежит = if it lies/sits for a while

Russian often uses the perfective non-past form after если when talking about a future condition with a result.

So если он полежит на кухне пару дней means something like:

• if it sits in the kitchen for a couple of days
• if it stays there for a couple of days

That sounds much more natural here than лежит.

Полежит comes from полежать, the perfective partner of лежать.

• лежать = to lie, to be lying
• полежать = to lie for a while

The prefix по- often adds the idea of doing something for some time.

So:

• он полежит пару дней = it lies/sits there for a couple of days

In this sentence, полежит fits well because the speaker is talking about the banana staying there long enough to become softer.

Yes, word-for-word it may look strange to an English speaker, but Russian prepositions do not match English one-to-one.

In Russian, на кухне is the normal way to say in the kitchen.

So you should learn it as a set phrase:

• на кухне = in the kitchen

This is idiomatic Russian, not a literal on top of the kitchen meaning.

Пару дней means for a couple of days.

Here is the structure:

• пару = a couple (accusative form of пара)
• дней = genitive plural of день

Russian often uses the accusative to express duration of time:

• час / часа
• день / два дня
• пару дней

So полежит на кухне пару дней means stays in the kitchen for a couple of days.

Because если introduces a subordinate clause, and Russian normally separates that clause with a comma.

So:

• Банан мягче, чем груша, если он полежит на кухне пару дней.

If you reverse the order, you still use a comma:

• Если он полежит на кухне пару дней, банан мягче, чем груша.

This is a standard Russian punctuation rule.

Yes. Russian word order is more flexible than English, and changing it often changes the emphasis, not the basic meaning.

For example, you could say:

• Если он полежит на кухне пару дней, банан мягче, чем груша.

That puts more focus on the condition first.

The original sentence starts with the main statement and then adds the condition, which sounds natural and conversational.